stevieg89

my friend is looking at lpg for when he gets a WRX STI and was asking me about it today, these are some of the things he asked me which i didnt know about

whats the difference in power between lpg and petrol. is there any difference in mpg. he is looking to get it to around 700bhp, what bhp will be feasble on gas. what problems if any are there with a turbo car running petrol/lpg

any more info and guides on gas conversion, parts and installation would be great as im not really clued up on lpg much but know a bit but to my friend lpg is totally new

thanks
Steve

290 AND READY

**** me - 700bhp on lpg gas!!!!!!!!!!
Dont know much about it but that sounds far too high a power band to run just lpg

scoobyboy

and the heads are not modified to take the gas either the valve clearences will close up rather quickly

stevieg89

hes not trying to run 700bhp on gas that would be impossible on that lump. petrols for hoofing mode and startup and gas is just for around town and motorway driving. what are lpg cars like on motorway aswell

Damocell

iTrader: (1)

have a look here: https://www.scoobynet.com/projects-4...g-project.html

and here :Scooby LPG

I also have a V3 WRX converted to gas, not quite setup right but there isn't that much difference.

Welloilbeefooked is the best person to speak to he has mapped his own PowerFC as well as the gas system together I think he getts roughly the same power now on LPG.

FWIW it costs me under £10 of gas to do 100 miles at the moment.

Damo

Damocell

iTrader: (1)

Just for completeness there is no difference on LPG or petrol as long as they are setup correctly.

My car runs 276bhp and waynes is over 350bhp IIRC, that is purely on gas.

If your mate wants to run big power you could setup to run gas in the low to mid range and automatically flick to petrol at the top end. or there are systems that can run gas and petrol at the top end to increase the power.

Best bet is to talk to a specialist

Damo

eggy

my mate runs his dodge ram(viper v10 engine) on lpg, about 570bhp, and there doesnt feel any difference on petrol or gas ,except price SUL=89PLITRE
LPG=59P LITRE

eggy790

iTrader: (20)

wow this thread sounds like it'll be interesting, so i'll keep an eye out

Damocell

iTrader: (1)

LPG is 45.9p in Barnsley!

Damo

stevieg89

ya gonna be waiting a while as hes getting the lpg conversion car in about a years time



anymore info on running petrol in the top end would be great especially an auto switching setup and running a analogue fuel gauge like the one on the dash but in a pod like boost gauges

EDIT: i forgot to ask this yesterday, does the exhaust note change at all and will it still have the scooby rumble while running on gas, are decats legal on an lpg vehicle. also is insurance affected if converted to lpg

stevieg89

bump

Damocell

iTrader: (1)

The systems can be set to switch over automatically betweem LPG and petrol at a given rpm which is set in the LPG ECU by the user. Some systescan run both gas and petrol.

Exhaust note doesn't change.

Decat is still legal but the emmisions arte less on LPG, if it is certified you get lower tax if you reg with DVLA.

Also LPG vehicles get free parking in Sheffield if you register and I think they are not subject to the congestion charge, but don't quote me on that.

Insurance shouldn't be affected but you will have to declare it.

Damo

merlin24

iTrader: (1)

Agree with that - valve seat degradation can be an issue with LPG.

Damocell

iTrader: (1)

Depends if you have hard valve seats or not, I am informed that the V3 WRX has got hard valve seats.

If they are soft valve seats you need a flash lube kit which costs about £40. Or a system that runs both LPG and petrol. This then cures the problem

Damo

teambpl67

I have a 97 forester turbo jdm, on lpg and have just had to do the valve clearances after 47,000 miles on gas so I would say it is an issue but not that big a price to pay. at the minute I am paying 41.9 for gas in Barnsley, when I first converted in 06 it was 33.5!!! Happy days

dannytwo

iTrader: (5)

Would this affect how much road tax you would pay?

Damocell

iTrader: (1)

Where in Barnsley is 41.9p???? I have been getting it for 45.9p

Damo

Welloilbeefhooked

iTrader: (3)

Now then ugly!!

Got you message the other day but was out of coverage in the lakes for a week.

Give me a call between 10am and 2pm any day this week.

Just to add a few points, my MY98 WRX has over 17k on it since LPG conversion. It does not appear to have any valve issues, but I do use flashlube. AFAIK, the valve seat issue would be the same for most cars and as long as it is set up correctly then there should be no more issues than running on petrol. Remember that any petrol car over time will have the valves receeding into the heads, its just that this happens faster on LPG.

Petrol, unleaded anyway, doesn't really add any valve lubrication other than the dirt created during combustion. It does however have a cooling effect.

I know of a guy in Poland who runs his STI on LPG. He has recently replaced 3 valves as they had burnt out in under 5k miles. He has said that after having his fueling checked for the LPG it was running way too weak. This is a really common story with LPG setups and the main reason why it gets a bad press.

If I get any valve wear then I will deal with it but at present its fine. I have both wideband AFR and EGT gauges in the dash, which spend most of their time switched off to avoid me watching them and not the road. It helps to see what is happening while tuning the LPG.

With ref to the setup, I have had mine at 1.45bar boost soley on LPG. I now have it set so that anything above 1.2 bar returns the system to petrol which is flawless. You can run a few ms of petrol all the time if you prefer. So mine mainly stays on LPG and swaps to petrol when flooring it.

I have since converted an IS200 and a BMW 320CI without a hitch. Both run fine and the BMW should be fine without flashlube while the IS has known issues with valves and LPG so have a lube kit installed.


I can't see me ever having a petrol car that doesn't run on LPG. I have been looking at an M3 to see if I can easily convert it. Its only the placement of the parts that worries me.

A good place for info is LPG Discussion Forum

Wayne.

johno_2k1

i dont like lpg on a car like this if your botherd about the pennys get a smart car or a bike , the impreza is ment to drink the stuff u just have to tske the fack and in my experience with gas u lose about 10% power on it good if your doing alot of miles but i would just change car

gsw

The only Subaru engine to be affected by valve seat recision are the ones fitted in to Foresters , non of the turbo engines have had any issues that i am aware of and i have done loads of them.

Flashlube systems dont work so well on Turbo engine because they need vacuum to suck the fluid in so obviously when they come on boost they stop working.

Welloilbeefhooked

iTrader: (3)

I see your point, although the on boost issue is for around 5% of the engine use for a raod car so its not a major concern for me.

Welloilbeefhooked

iTrader: (3)

What a well thought out post. I have the performance AND the fuel economy. If you wish to pour your money away, please do so.

I prefer to have my cake AND eat it!!

Wayne.